Tallinn, Estonia has three layers. The first is bonny Tallinn, with its perfect medieval UNESCO old town. The second is post-Soviet Tallinn, a grey decaying relic of the former occupation. The third is hipster Tallinn, drinking craft beer and spray painting the town. To understand the city, you really should explore all three.
The first fortress was built in Tallinn in 1050. The city experienced successive waves of occupation from the Germans, the Swedes, the Russians, the Germans (again) and (yet again) the Russians, before finally achieving their independence in 1990. Tallinn was fortunate because it was never fully pillaged or razed, and while it got damaged in WWII, it wasn’t destroyed. So, what you’ll find there is a complex layer cake of history with a very pretty UNESCO heritage frosting on top.
Top Historic Spots: Wandering around Old Town, killer views at the Kohtuotsa viewing platform, touring the Bastion Passages, exploring seafaring history at the Seaplane Harbor museum and finding royalty at Kadriorg Park.